Magnetic field sensors are widely used in a number of applications including in, for example, compass, security, and military applications, geophysics and space research, biomagnetism and medical applications, and non-destructive testing. Magnetic field sensors are typically based on semiconductor materials (e.g., Hall sensors, semiconductor magnetoresistors, and so forth) and ferromagnetic materials (e.g., ferromagnetic magnetoresistors and flux guides). Other magnetic sensors utilize optical, resonant, and superconducting properties.